For many years, liners have been used to repair damaged pipelines such as sewer lines. Such liners typically include a tubular structure made from an absorbent material which is impregnated with resin. Whilst the resin is uncured, the liner is shaped to match the section of pipeline which it is intended to line and is then held in that position until the resin is cured. The liner is pressed firmly against the section of pipeline during curing to ensure that the cross-sectional opening defined by the liner is maximised. After curing, the tubular structure forms a rigid layer that remains in place within the pipeline thereby forming a lining within that section of the pipeline.
Although techniques for lining lengths of pipelines are well established there is still considerable difficulty in reliably lining the lateral connections to such pipelines. The “lateral connections” are the branch pipes or side pipes which lead from the main pipeline. For example, a main sewer pipeline will have a lateral connection to each house or property it services.
When sewer pipelines are laid, the lateral connections are normally made by fitting a “T” section in the main pipeline. However, in some instances in the past the lateral connections have been made by forming a hole in the main pipeline at the desired location and then inserting a side pipe directly into that hole. Connections of this type are particularly difficult to line because of the irregularity of the connection between the main pipeline and the side pipe.
Various different liners, methods and apparatus have been developed to line pipelines and their lateral connections. For example, U.S. Pat. No. 5,624,629 shows a liner for a lateral pipe wherein the liner is formed by a flexible lining tube 14 with a beaded end 16. The lining tube 14 and carrier tube 18 are inverted into the lateral 12 by pressurised fluid. The lining tube 14 lines the lateral pipe but does not include a tubular section that lines an inner circumferential portion of the adjacent main pipeline.
U.S. Pat. No. 5,927,341 describes a tailored assembly of a flexible resin absorbent material for lining a lateral connection. The tailored assembly includes a main pipe tubular structure 22 and an extension tubular structure 24 that has a collar 26. The tubular structure 24 projects through an aperture 27 in the main tubular structure so that the collar 26 abuts against the inner surface of the tubular structure 24. Hence, it will be appreciated that the assembly (i.e. the liner) is actually a two-piece assembly.
U.S. Pat. No. 6,044,867 describes a method and apparatus for fabricating a resin impregnable liner for lining a lateral pipe. The liner is in the form of a “top hat” and does not include a tubular section that lines an inner circumferential portion of the adjacent main pipeline.
The applicant's own earlier Australian patent 2003244547 describes an apparatus and method for repairing the lateral or branch connections of pipelines. As most clearly shown in FIGS. 10 and 11 of that patent, the textile liner 60 includes a main tubular passage 62 and a branch tubular passage 63 that are stitched or otherwise joined together in the same way as a sleeve is sewn into an arm hole of a shirt. Accordingly, a circumferential seam is established where the branch tubular passage 63 is connected to the main tubular passage 62.
The present invention relates to a liner for a lateral connection that lines an inner circumferential portion of a lateral pipe and an inner circumferential portion of the adjacent main pipeline. More particularly, the invention aims to preferably provide a liner of such a type that is easier to manufacture than prior art liners.
The present invention also seeks to preferably provide a liner that better conforms to the shape of the inner surface of the portion of the pipeline being lined.
The discussion of the background to the invention herein is included to explain the context of the invention. This is not to be taken as an admission that any of the material referred to was published, known or part of the common general knowledge as at the priority date of this application.